tick_check_replacement() returns if a replacement of clock_event_device is
possible or not. It does this as the first check:

	if (tick_check_percpu(curdev, newdev, smp_processor_id()))
		return false;

Thats wrong. tick_check_percpu() returns true when the device is
useable. Check for false instead.

[ tglx: Massaged changelog ]
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Cc: <stable@vger.kernel.org> # v3.11+
Cc: linaro-kernel@lists.linaro.org
Cc: fweisbec@gmail.com
Cc: Arvind.Chauhan@arm.com
Cc: linaro-networking@linaro.org
Link: http://lkml.kernel.org/r/486a02efe0246635aaba786e24b42d316438bf3b.1397537987.git.viresh.kumar@linaro.orgSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

To increase compiler portability there is <linux/compiler.h> which
provides convenience macros for various gcc constructs.  Eg: __weak for
__attribute__((weak)).  I've replaced all instances of gcc attributes
with the right macro in the kernel subsystem.
Signed-off-by: NGideon Israel Dsouza <gidisrael@gmail.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

In commit 47a1b796 ("tick/timekeeping: Call
update_wall_time outside the jiffies lock"), we moved to calling
clock_was_set() due to the fact that we were no longer holding
the timekeeping or jiffies lock.

However, there is still the problem that clock_was_set()
triggers an IPI, which cannot be done from the timer's hard irq
context, and will generate WARN_ON warnings.

Apparently in my earlier testing, I'm guessing I didn't bump the
dmesg log level, so I somehow missed the WARN_ONs.

Thus we need to revert back to calling clock_was_set_delayed().
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1395963049-11923-1-git-send-email-john.stultz@linaro.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

tick_handle_periodic() is calling ktime_add() at two places, first before the
infinite loop and then at the end of infinite loop. We can rearrange code a bit
to fix code duplication here.

It looks quite simple and shouldn't break anything, I guess :)
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Cc: linaro-kernel@lists.linaro.org
Cc: fweisbec@gmail.com
Link: http://lkml.kernel.org/r/be3481e8f3f71df694a4b43623254fc93ca51b59.1395735873.git.viresh.kumar@linaro.orgSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

One of the comments in tick_handle_periodic() had 'when' instead of 'which' (My
guess :)). Fix it.

Also fix spelling mistake in 'Possible'.
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Cc: linaro-kernel@lists.linaro.org
Cc: skarafotis@gmail.com
Link: http://lkml.kernel.org/r/2b29ca4230c163e44179941d7c7a16c1474385c2.1395743878.git.viresh.kumar@linaro.orgSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

Include appropriate header file kernel/time/timekeeping_internal.h in
kernel/time/timekeeping_debug.c because it has prototype declaration of
function defined in kernel/time/timekeeping_debug.c.

This eliminates the following warning in
kernel/time/timekeeping_debug.c:
kernel/time/timekeeping_debug.c:68:6: warning: no previous prototype for ‘tk_debug_account_sleep_time’ [-Wmissing-prototypes]
Signed-off-by: NRashika Kheria <rashika.kheria@gmail.com>
Reviewed-by: NJosh Triplett <josh@joshtriplett.org>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

The generic sched_clock registration function was previously
done lockless, due to the fact that it was expected to be called
only once. However, now there are systems that may register
multiple sched_clock sources, for which the lack of locking has
casued problems:

If two sched_clock sources are registered we may end up in a
situation where a call to sched_clock() may be accessing the
epoch cycle count for the old counter and the cycle count for the
new counter. This can lead to confusing results where
sched_clock() values jump and then are reset to 0 (due to the way
the registration function forces the epoch_ns to be 0).

Fix this by reorganizing the registration function to hold the
seqlock for as short a time as possible while we update the
clock_data structure for a new counter. We also put any
accumulated time into epoch_ns instead of resetting the time to
0 so that the clock doesn't reset after each successful
registration.

[jstultz: Added extra context to the commit message]
Reported-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NStephen Boyd <sboyd@codeaurora.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Josh Cartwright <joshc@codeaurora.org>
Link: http://lkml.kernel.org/r/1392662736-7803-2-git-send-email-john.stultz@linaro.orgSigned-off-by: NJohn Stultz <john.stultz@linaro.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

This bit of information is in the Kconfig help text:

  "Note the boot CPU will still be kept outside the range to
  handle the timekeeping duty."

However neither the variable NO_HZ_FULL_ALL, or the prompt
convey this important detail, so lets add it to the prompt
to make it more explicitly obvious to the average user.
Acked-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1391711781-7466-1-git-send-email-paul.gortmaker@windriver.comSigned-off-by: NFrederic Weisbecker <fweisbec@gmail.com>

AMD systems which use the C1E workaround in the amd_e400_idle routine
trigger the WARN_ON_ONCE in the broadcast code when onlining a CPU.

The reason is that the idle routine of those AMD systems switches the
cpu into forced broadcast mode early on before the newly brought up
CPU can switch over to high resolution / NOHZ mode. The timer related
CPU1 bringup looks like this:

  clockevent_register_device(local_apic);
  tick_setup(local_apic);
  ...
  idle()
	tick_broadcast_on_off(FORCE);
	tick_broadcast_oneshot_control(ENTER)
	  cpumask_set(cpu, broadcast_oneshot_mask);
	halt();

Now the broadcast interrupt on CPU0 sets CPU1 in the
broadcast_pending_mask and wakes CPU1. So CPU1 continues:

	local_apic_timer_interrupt()
	   tick_handle_periodic();
	   softirq()
	     tick_init_highres();
	       cpumask_clr(cpu, broadcast_oneshot_mask);
	
	tick_broadcast_oneshot_control(ENTER)
	   WARN_ON(cpumask_test(cpu, broadcast_pending_mask);

So while we remove CPU1 from the broadcast_oneshot_mask when we switch
over to highres mode, we do not clear the pending bit, which then
triggers the warning when we go back to idle.

The reason why this is only visible on C1E affected AMD systems is
that the other machines enter the deep sleep states via
acpi_idle/intel_idle and exit the broadcast mode before executing the
remote triggered local_apic_timer_interrupt. So the pending bit is
already cleared when the switch over to highres mode is clearing the
oneshot mask.

The solution is simple: Clear the pending bit together with the mask
bit when we switch over to highres mode.

Stanislaw came up independently with the same patch by enforcing the
C1E workaround and debugging the fallout. I picked mine, because mine
has a changelog :)
Reported-by: Npoma <pomidorabelisima@gmail.com>
Debugged-by: NStanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Olaf Hering <olaf@aepfle.de>
Cc: Dave Jones <davej@redhat.com>
Cc: Justin M. Forbes <jforbes@redhat.com>
Cc: Josh Boyer <jwboyer@redhat.com>
Link: http://lkml.kernel.org/r/alpine.DEB.2.02.1402111434180.21991@ionos.tec.linutronix.de
Cc: stable@vger.kernel.org # 3.10+
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

The hrtimer mode of broadcast is supported only when
GENERIC_CLOCKEVENTS_BROADCAST and TICK_ONESHOT config options
are enabled. Hence compile in the functions for hrtimer mode
of broadcast only when these options are selected.
Also fix max_delta_ticks value for the pseudo clock device.
Reported-by: NFengguang Wu <fengguang.wu@intel.com>
Reported-by: NIngo Molnar <mingo@kernel.org>
Signed-off-by: NPreeti U Murthy <preeti@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/52F719EE.9010304@linux.vnet.ibm.comSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

Make the stub function static inline instead of static and move the
clockevents related function into the proper ifdeffed section.
Reported-by: NFengguang Wu <fengguang.wu@intel.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Soren Brinkmann <soren.brinkmann@xilinx.com>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>

On some architectures, in certain CPU deep idle states the local timers stop.
An external clock device is used to wakeup these CPUs. The kernel support for the
wakeup of these CPUs is provided by the tick broadcast framework by using the
external clock device as the wakeup source.

However not all implementations of architectures provide such an external
clock device. This patch includes support in the broadcast framework to handle
the wakeup of the CPUs in deep idle states on such systems by queuing a hrtimer
on one of the CPUs, which is meant to handle the wakeup of CPUs in deep idle states.

This patchset introduces a pseudo clock device which can be registered by the
archs as tick_broadcast_device in the absence of a real external clock
device. Once registered, the broadcast framework will work as is for these
architectures as long as the archs take care of the BROADCAST_ENTER
notification failing for one of the CPUs. This CPU is made the stand by CPU to
handle wakeup of the CPUs in deep idle and it *must not enter deep idle states*.

The CPU with the earliest wakeup is chosen to be this CPU. Hence this way the
stand by CPU dynamically moves around and so does the hrtimer which is queued
to trigger at the next earliest wakeup time. This is consistent with the case where
an external clock device is present. The smp affinity of this clock device is
set to the CPU with the earliest wakeup. This patchset handles the hotplug of
the stand by CPU as well by moving the hrtimer on to the CPU handling the CPU_DEAD
notification.

Originally-from: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NPreeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: deepthi@linux.vnet.ibm.com
Cc: paulmck@linux.vnet.ibm.com
Cc: fweisbec@gmail.com
Cc: paulus@samba.org
Cc: srivatsa.bhat@linux.vnet.ibm.com
Cc: svaidy@linux.vnet.ibm.com
Cc: peterz@infradead.org
Cc: benh@kernel.crashing.org
Cc: rafael.j.wysocki@intel.com
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/20140207080632.17187.80532.stgit@preeti.in.ibm.comSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

The broadcast framework can potentially be made use of by archs which do not have an
external clock device as well. Then, it is required that one of the CPUs need
to handle the broadcasting of wakeup IPIs to the CPUs in deep idle. As a
result its local timers should remain functional all the time. For such
a CPU, the BROADCAST_ENTER notification has to fail indicating that its clock
device cannot be shutdown. To make way for this support, change the return
type of tick_broadcast_oneshot_control() and hence clockevents_notify() to
indicate such scenarios.
Signed-off-by: NPreeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: deepthi@linux.vnet.ibm.com
Cc: paulmck@linux.vnet.ibm.com
Cc: fweisbec@gmail.com
Cc: paulus@samba.org
Cc: srivatsa.bhat@linux.vnet.ibm.com
Cc: svaidy@linux.vnet.ibm.com
Cc: peterz@infradead.org
Cc: benh@kernel.crashing.org
Cc: rafael.j.wysocki@intel.com
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/20140207080606.17187.78306.stgit@preeti.in.ibm.comSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

clockevent devices in periodic mode are not updated when the frequency
of the device changes. Issue a dev->set_mode() callback which forces
the device to reevaluate the timer settings.
Signed-off-by: NSoren Brinkmann <soren.brinkmann@xilinx.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Michal Simek <michal.simek@xilinx.com>
Link: http://lkml.kernel.org/r/1391466877-28908-3-git-send-email-soren.brinkmann@xilinx.comSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

We can identify the broadcast device in the core and serialize all
callers including interrupts on a different CPU against the update.
Also, disabling interrupts is moved into the core allowing callers to
leave interrutps enabled when calling clockevents_update_freq().
Signed-off-by: NSoren Brinkmann <soren.brinkmann@xilinx.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Soeren Brinkmann <soren.brinkmann@xilinx.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Michal Simek <michal.simek@xilinx.com>
Link: http://lkml.kernel.org/r/1391466877-28908-2-git-send-email-soren.brinkmann@xilinx.comSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

For better use of CPU idle time, allow the scheduler to select the CPU
on which the CMOS clock sync work would be scheduled. This improves
idle residency time and conserver power.

This functionality is enabled when CONFIG_WQ_POWER_EFFICIENT is selected.
Signed-off-by: NShaibal Dutta <shaibal.dutta@broadcom.com>
[zoran.markovic@linaro.org: Added commit message. Aligned code.]
Signed-off-by: NZoran Markovic <zoran.markovic@linaro.org>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/1391195904-12497-1-git-send-email-zoran.markovic@linaro.orgSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

When compiling for the IA-64 ski emulator, HZ is set to 32 because the
emulation is slow and we don't want to waste too many cycles processing
timers. Alpha also has an option to set HZ to 32.

This causes integer underflow in
kernel/time/jiffies.c:
kernel/time/jiffies.c:66:2: warning: large integer implicitly truncated to unsigned type [-Woverflow]
  .mult  = NSEC_PER_JIFFY << JIFFIES_SHIFT, /* details above */
  ^

This patch reduces the JIFFIES_SHIFT value to avoid the overflow.
Signed-off-by: NMikulas Patocka <mikulas@artax.karlin.mff.cuni.cz>
Link: http://lkml.kernel.org/r/alpine.LRH.2.02.1401241639100.23871@file01.intranet.prod.int.rdu2.redhat.com
Cc: stable@vger.kernel.org
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Code usually starts with 'tab' instead of 7 'space' in kernel
Signed-off-by: NAlex Shi <alex.shi@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Alex Shi <alex.shi@linaro.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Kevin Hilman <khilman@linaro.org>
Link: http://lkml.kernel.org/r/1386074112-30754-2-git-send-email-alex.shi@linaro.orgSigned-off-by: NFrederic Weisbecker <fweisbec@gmail.com>

We don't need to fetch the timekeeping max deferment under the
jiffies_lock seqlock.

If the clocksource is updated concurrently while we stop the tick,
stop machine is called and the tick will be reevaluated again along with
uptodate jiffies and its related values.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Alex Shi <alex.shi@linaro.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Kevin Hilman <khilman@linaro.org>
Link: http://lkml.kernel.org/r/1387320692-28460-9-git-send-email-fweisbec@gmail.comSigned-off-by: NFrederic Weisbecker <fweisbec@gmail.com>

This makes the code more symetric against the existing tick functions
called on irq exit: tick_irq_exit() and tick_nohz_irq_exit().

These function are also symetric as they mirror each other's action:
we start to account idle time on irq exit and we stop this accounting
on irq entry. Also the tick is stopped on irq exit and timekeeping
catches up with the tickless time elapsed until we reach irq entry.

This rename was suggested by Peter Zijlstra a long while ago but it
got forgotten in the mass.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Alex Shi <alex.shi@linaro.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Kevin Hilman <khilman@linaro.org>
Link: http://lkml.kernel.org/r/1387320692-28460-2-git-send-email-fweisbec@gmail.comSigned-off-by: NFrederic Weisbecker <fweisbec@gmail.com>

In order to avoid the runtime condition and variable load turn
sched_clock_stable into a static_key.

Also provide a shorter implementation of local_clock() and
cpu_clock(int) when sched_clock_stable==1.

                        MAINLINE   PRE       POST

    sched_clock_stable: 1          1         1
    (cold) sched_clock: 329841     221876    215295
    (cold) local_clock: 301773     234692    220773
    (warm) sched_clock: 38375      25602     25659
    (warm) local_clock: 100371     33265     27242
    (warm) rdtsc:       27340      24214     24208
    sched_clock_stable: 0          0         0
    (cold) sched_clock: 382634     235941    237019
    (cold) local_clock: 396890     297017    294819
    (warm) sched_clock: 38194      25233     25609
    (warm) local_clock: 143452     71234     71232
    (warm) rdtsc:       27345      24245     24243
Signed-off-by: NPeter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/n/tip-eummbdechzz37mwmpags1gjr@git.kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

Unfortunately the seqlock lockdep enablement can't be used
in sched_clock(), since the lockdep infrastructure eventually
calls into sched_clock(), which causes a deadlock.

Thus, this patch changes all generic sched_clock() usage
to use the raw_* methods.
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: NStephen Boyd <sboyd@codeaurora.org>
Reported-by: NKrzysztof Hałasa <khalasa@piap.pl>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Cc: Willy Tarreau <w@1wt.eu>
Signed-off-by: NPeter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1388704274-5278-2-git-send-email-john.stultz@linaro.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

Prior to 92bb1fcf (Only
do nanosecond rounding on GENERIC_TIME_VSYSCALL_OLD
systems), the comment here was accuate, but now we can
mostly avoid the extra rounding which causes the unlikey
to be actually likely here.

So remove the out of date comment.
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

Fix trivial comment typo for tk_setup_internals().
Signed-off-by: NYijing Wang <wangyijing@huawei.com>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

Since 48cdc135 (Implement a shadow timekeeper), we have to
call timekeeping_update() after any adjustment to the timekeeping
structure in order to make sure that any adjustments to the structure
persist.

In the timekeeping suspend path, we udpate the timekeeper
structure, so we should be sure to update the shadow-timekeeper
before releasing the timekeeping locks. Currently this isn't done.

In most cases, the next time related code to run would be
timekeeping_resume, which does update the shadow-timekeeper, but
in an abundence of caution, this patch adds the call to
timekeeping_update() in the suspend path.

Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: stable <stable@vger.kernel.org> #3.10+
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

A think-o in the calculation of the monotonic -> tai time offset
results in CLOCK_TAI timers and nanosleeps to expire late (the
latency is ~2x the tai offset).

Fix this by adding the tai offset from the realtime offset instead
of subtracting.

Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: stable <stable@vger.kernel.org> #3.10+
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

Since the xtime lock was split into the timekeeping lock and
the jiffies lock, we no longer need to call update_wall_time()
while holding the jiffies lock.

Thus, this patch splits update_wall_time() out from do_timer().

This allows us to get away from calling clock_was_set_delayed()
in update_wall_time() and instead use the standard clock_was_set()
call that previously would deadlock, as it causes the jiffies lock
to be acquired.

Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

As part of normal operaions, the hrtimer subsystem frequently calls
into the timekeeping code, creating a locking order of
  hrtimer locks -> timekeeping locks

clock_was_set_delayed() was suppoed to allow us to avoid deadlocks
between the timekeeping the hrtimer subsystem, so that we could
notify the hrtimer subsytem the time had changed while holding
the timekeeping locks. This was done by scheduling delayed work
that would run later once we were out of the timekeeing code.

But unfortunately the lock chains are complex enoguh that in
scheduling delayed work, we end up eventually trying to grab
an hrtimer lock.

Sasha Levin noticed this in testing when the new seqlock lockdep
enablement triggered the following (somewhat abrieviated) message:

[  251.100221] ======================================================
[  251.100221] [ INFO: possible circular locking dependency detected ]
[  251.100221] 3.13.0-rc2-next-20131206-sasha-00005-g8be2375-dirty #4053 Not tainted
[  251.101967] -------------------------------------------------------
[  251.101967] kworker/10:1/4506 is trying to acquire lock:
[  251.101967]  (timekeeper_seq){----..}, at: [<ffffffff81160e96>] retrigger_next_event+0x56/0x70
[  251.101967]
[  251.101967] but task is already holding lock:
[  251.101967]  (hrtimer_bases.lock#11){-.-...}, at: [<ffffffff81160e7c>] retrigger_next_event+0x3c/0x70
[  251.101967]
[  251.101967] which lock already depends on the new lock.
[  251.101967]
[  251.101967]
[  251.101967] the existing dependency chain (in reverse order) is:
[  251.101967]
-> #5 (hrtimer_bases.lock#11){-.-...}:
[snipped]
-> #4 (&rt_b->rt_runtime_lock){-.-...}:
[snipped]
-> #3 (&rq->lock){-.-.-.}:
[snipped]
-> #2 (&p->pi_lock){-.-.-.}:
[snipped]
-> #1 (&(&pool->lock)->rlock){-.-...}:
[  251.101967]        [<ffffffff81194803>] validate_chain+0x6c3/0x7b0
[  251.101967]        [<ffffffff81194d9d>] __lock_acquire+0x4ad/0x580
[  251.101967]        [<ffffffff81194ff2>] lock_acquire+0x182/0x1d0
[  251.101967]        [<ffffffff84398500>] _raw_spin_lock+0x40/0x80
[  251.101967]        [<ffffffff81153e69>] __queue_work+0x1a9/0x3f0
[  251.101967]        [<ffffffff81154168>] queue_work_on+0x98/0x120
[  251.101967]        [<ffffffff81161351>] clock_was_set_delayed+0x21/0x30
[  251.101967]        [<ffffffff811c4bd1>] do_adjtimex+0x111/0x160
[  251.101967]        [<ffffffff811e2711>] compat_sys_adjtimex+0x41/0x70
[  251.101967]        [<ffffffff843a4b49>] ia32_sysret+0x0/0x5
[  251.101967]
-> #0 (timekeeper_seq){----..}:
[snipped]
[  251.101967] other info that might help us debug this:
[  251.101967]
[  251.101967] Chain exists of:
  timekeeper_seq --> &rt_b->rt_runtime_lock --> hrtimer_bases.lock#11

[  251.101967]  Possible unsafe locking scenario:
[  251.101967]
[  251.101967]        CPU0                    CPU1
[  251.101967]        ----                    ----
[  251.101967]   lock(hrtimer_bases.lock#11);
[  251.101967]                                lock(&rt_b->rt_runtime_lock);
[  251.101967]                                lock(hrtimer_bases.lock#11);
[  251.101967]   lock(timekeeper_seq);
[  251.101967]
[  251.101967]  *** DEADLOCK ***
[  251.101967]
[  251.101967] 3 locks held by kworker/10:1/4506:
[  251.101967]  #0:  (events){.+.+.+}, at: [<ffffffff81154960>] process_one_work+0x200/0x530
[  251.101967]  #1:  (hrtimer_work){+.+...}, at: [<ffffffff81154960>] process_one_work+0x200/0x530
[  251.101967]  #2:  (hrtimer_bases.lock#11){-.-...}, at: [<ffffffff81160e7c>] retrigger_next_event+0x3c/0x70
[  251.101967]
[  251.101967] stack backtrace:
[  251.101967] CPU: 10 PID: 4506 Comm: kworker/10:1 Not tainted 3.13.0-rc2-next-20131206-sasha-00005-g8be2375-dirty #4053
[  251.101967] Workqueue: events clock_was_set_work

So the best solution is to avoid calling clock_was_set_delayed() while
holding the timekeeping lock, and instead using a flag variable to
decide if we should call clock_was_set() once we've released the locks.

This works for the case here, where the do_adjtimex() was the deadlock
trigger point. Unfortuantely, in update_wall_time() we still hold
the jiffies lock, which would deadlock with the ipi triggered by
clock_was_set(), preventing us from calling it even after we drop the
timekeeping lock. So instead call clock_was_set_delayed() at that point.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: stable <stable@vger.kernel.org> #3.10+
Reported-by: NSasha Levin <sasha.levin@oracle.com>
Tested-by: NSasha Levin <sasha.levin@oracle.com>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

In 780427f0 (Indicate that clock was set in the pvclock
gtod notifier), logic was added to pass a CLOCK_WAS_SET
notification to the pvclock notifier chain.

While that patch added a action flag returned from
accumulate_nsecs_to_secs(), it only uses the returned value
in one location, and not in the logarithmic accumulation.

This means if a leap second triggered during the logarithmic
accumulation (which is most likely where it would happen),
the notification that the clock was set would not make it to
the pv notifiers.

This patch extends the logarithmic_accumulation pass down
that action flag so proper notification will occur.

This patch also changes the varialbe action -> clock_set
per Ingo's suggestion.

Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: <xen-devel@lists.xen.org>
Cc: stable <stable@vger.kernel.org> #3.11+
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

Since 48cdc135 (Implement a shadow timekeeper), we have to
call timekeeping_update() after any adjustment to the timekeeping
structure in order to make sure that any adjustments to the structure
persist.

Unfortunately, the updates to the tai offset via adjtimex do not
trigger this update, causing adjustments to the tai offset to be
made and then over-written by the previous value at the next
update_wall_time() call.

This patch resovles the issue by calling timekeeping_update()
right after setting the tai offset.

Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: stable <stable@vger.kernel.org> #3.10+
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

A few functions use remote per CPU access APIs when they
deal with local values.

Just do the right conversion to improve performance, code
readability and debug checks.

While at it, lets extend some of these function names with *_this_cpu()
suffix in order to display their purpose more clearly.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>

If CONFIG_NO_HZ=n tick_nohz_get_sleep_length() returns NSEC_PER_SEC/HZ.

If CONFIG_NO_HZ=y and the nohz functionality is disabled via the
command line option "nohz=off" or not enabled due to missing hardware
support, then tick_nohz_get_sleep_length() returns 0. That happens
because ts->sleep_length is never set in that case.

Set it to NSEC_PER_SEC/HZ when the NOHZ mode is inactive.
Reported-by: NMichal Hocko <mhocko@suse.cz>
Reported-by: NBorislav Petkov <bp@alien8.de>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Since commit 1e75fa8b (time: Condense timekeeper.xtime
into xtime_sec - merged in v3.6), there has been an problem
with the error accounting in the timekeeping code, such that
when truncating to nanoseconds, we round up to the next nsec,
but the balancing adjustment to the ntp_error value was dropped.

This causes 1ns per tick drift forward of the clock.

In 3.7, this logic was isolated to only GENERIC_TIME_VSYSCALL_OLD
architectures (s390, ia64, powerpc).

The fix is simply to balance the accounting and to subtract the
added nanosecond from ntp_error. This allows the internal long-term
clock steering to keep the clock accurate.

While this fix removes the regression added in 1e75fa8b, the
ideal solution is to move away from GENERIC_TIME_VSYSCALL_OLD
and use the new VSYSCALL method, which avoids entirely the
nanosecond granular rounding, and the resulting short-term clock
adjustment oscillation needed to keep long term accurate time.

[ jstultz: Many thanks to Martin for his efforts identifying this
  	   subtle bug, and providing the fix. ]

Originally-from: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Paul Turner <pjt@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: stable <stable@vger.kernel.org>  #v3.6+
Link: http://lkml.kernel.org/r/1385149491-20307-1-git-send-email-john.stultz@linaro.orgSigned-off-by: NJohn Stultz <john.stultz@linaro.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Taken straight from a tglx email ;)
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

RCU and the fine grained idle time accounting functions check
tick_nohz_enabled. But that variable is merily telling that NOHZ has
been enabled in the config and not been disabled on the command line.

But it does not tell anything about nohz being active. That's what all
this should check for.

Matthew reported, that the idle accounting on his old P1 machine
showed bogus values, when he enabled NOHZ in the config and did not
disable it on the kernel command line. The reason is that his machine
uses (refined) jiffies as a clocksource which explains why the "fine"
grained accounting went into lala land, because it depends on when the
system goes and leaves idle relative to the jiffies increment.

Provide a tick_nohz_active indicator and let RCU and the accounting
code use this instead of tick_nohz_enable.
Reported-and-tested-by: NMatthew Whitehead <tedheadster@gmail.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NSteven Rostedt <rostedt@goodmis.org>
Reviewed-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: john.stultz@linaro.org
Cc: mwhitehe@redhat.com
Link: http://lkml.kernel.org/r/alpine.DEB.2.02.1311132052240.30673@ionos.tec.linutronix.de

Marc Kleine-Budde pointed out, that commit 77cc982f "clocksource: use
clockevents_config_and_register() where possible" caused a regression
for some of the converted subarchs.

The reason is, that the clockevents core code converts the minimal
hardware tick delta to a nanosecond value for core internal
usage. This conversion is affected by integer math rounding loss, so
the backwards conversion to hardware ticks will likely result in a
value which is less than the configured hardware limitation. The
affected subarchs used their own workaround (SIGH!) which got lost in
the conversion.

The solution for the issue at hand is simple: adding evt->mult - 1 to
the shifted value before the integer divison in the core conversion
function takes care of it. But this only works for the case where for
the scaled math mult/shift pair "mult <= 1 << shift" is true. For the
case where "mult > 1 << shift" we can apply the rounding add only for
the minimum delta value to make sure that the backward conversion is
not less than the given hardware limit. For the upper bound we need to
omit the rounding add, because the backwards conversion is always
larger than the original latch value. That would violate the upper
bound of the hardware device.

Though looking closer at the details of that function reveals another
bogosity: The upper bounds check is broken as well. Checking for a
resulting "clc" value greater than KTIME_MAX after the conversion is
pointless. The conversion does:

      u64 clc = (latch << evt->shift) / evt->mult;

So there is no sanity check for (latch << evt->shift) exceeding the
64bit boundary. The latch argument is "unsigned long", so on a 64bit
arch the handed in argument could easily lead to an unnoticed shift
overflow. With the above rounding fix applied the calculation before
the divison is:

       u64 clc = (latch << evt->shift) + evt->mult - 1;

So we need to make sure, that neither the shift nor the rounding add
is overflowing the u64 boundary.

[ukl: move assignment to rnd after eventually changing mult, fix build
 issue and correct comment with the right math]
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Russell King - ARM Linux <linux@arm.linux.org.uk>
Cc: Marc Kleine-Budde <mkl@pengutronix.de>
Cc: nicolas.ferre@atmel.com
Cc: Marc Pignat <marc.pignat@hevs.ch>
Cc: john.stultz@linaro.org
Cc: kernel@pengutronix.de
Cc: Ronald Wahl <ronald.wahl@raritan.com>
Cc: LAK <linux-arm-kernel@lists.infradead.org>
Cc: Ludovic Desroches <ludovic.desroches@atmel.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1380052223-24139-1-git-send-email-u.kleine-koenig@pengutronix.deSigned-off-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>

sysfs_get_uname() is erroneously declared as returning size_t even
though it may return a negative value, specifically -EINVAL.  Its
callers then check whether its return value is less than zero and indeed
that is never the case for size_t.

This patch changes sysfs_get_uname() to return ssize_t and makes sure
its callers use ssize_t accordingly.
Signed-off-by: NPatrick Palka <patrick@parcs.ath.cx>
[jstultz: Didn't apply cleanly, as a similar partial fix was also applied
so had to resolve the collisions]
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

Fix some typos in timekeeping comments.
Signed-off-by: NXie XiuQi <xiexiuqi@huawei.com>
[jstultz: Commit message tweaks]
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

Fedora Ruby maintainer reported latest Ruby doesn't work on Fedora Rawhide
on ARM. (http://bugs.ruby-lang.org/issues/9008)

Because of, commit 1c6b39ad (alarmtimers: Return -ENOTSUPP if no
RTC device is present) intruduced to return ENOTSUPP when
clock_get{time,res} can't find a RTC device. However this is incorrect.

First, ENOTSUPP isn't exported to userland (ENOTSUP or EOPNOTSUP are the
closest userland equivlents).

Second, Posix and Linux man pages agree that clock_gettime and
clock_getres should return EINVAL if clk_id argument is invalid.
While the arugment that the clockid is valid, but just not supported
on this hardware could be made, this is just a technicality that
doesn't help userspace applicaitons, and only complicates error
handling.

Thus, this patch changes the code to use EINVAL.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: stable <stable@vger.kernel.org>  #3.0 and up
Reported-by: NVit Ondruch <v.ondruch@tiscali.cz>
Signed-off-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
[jstultz: Tweaks to commit message to include full rational]
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

Signed-off-by: NXie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>